This application claims the priority of Japanese Patent Application Nos. 10-89403 and 10-89404 filed on Mar. 17, 1998, Nos. 10-100097, 10-100098 and 10-100099 filed on Mar. 27, 1998 which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an air and water supply system for endoscopes, and more particularly, to an arrangement for flow control of air and water supply through air feed tubes and water feed tubes installed in endoscopes.
2. Description of the Prior Art
Endoscopes are conventionally provided with air feed tubes, water feed tubes, etc. through which air and water (liquid) are supplied to the tip of the endoscope to clean the viewing window (objective lens surfaces) at the tip or remove water-drops from it as well as to inflate a body cavity such as the stomach by the air sent into the body of the subject under observation. After use, endoscopes are cleaned and drained through the water feed tubes before storage.
FIG. 12 shows the configuration of a solenoid valve unit of a conventional endoscope. The water feed tube 2A and air feed tube 3A on the endoscope side are connected to the solenoid valve unit 1. The solenoid valve unit 1 comprises a water feed tube 2B, solenoid valve Va for controlling the opening and closing of the water feed tube 2B, air feed tube 3B, and solenoid valve Vb for controlling the opening and closing of the air feed tube 3B, wherein the water feed tube 2B is connected to a feed water tank 4 through a water feed tube 2C.
The solenoid valve unit 1 also contains an air and water supply pump 5, which is connected with the air feed tube 3B and a tube (air feed tube) for water supply 3C, which in turn is connected to the feed water tank 4 through a tube 3D. Furthermore the pump 5 is connected with an atmospheric escape pipe 6, which is equipped with a solenoid valve Vc. The control switch for air/water supply is installed, for example, on the operating section of the endoscope.
In the above configuration, when the air/water supply switch is not actuated, only the solenoid valve Vc remains open and the air sent from the pump 5 is released to the atmosphere through the atmospheric escape pipe 6. When the air/water supply switch is manipulated to supply water, the solenoid valve Va opens and the solenoid valves Vb and Vc close, allowing water to be supplied from the feed water tank 4 to the endoscope through the water feed tubes 2C, 2B, and 2A. When it is manipulated to supply air, the solenoid valve Vb opens and the solenoid valves Va and Vc close, allowing air to be supplied through the air feed tubes 3B and 3A.